Genetic diversity and population structure of Raffaelea quercus‐mongolicae,a fungus associated with oak mortality in South Korea

Raffaelea quercus‐mongolicae is a fungus associated with oak wilt and deemed to cause extensive oak mortality in South Korea. Since the discovery of this fungus on a dead Mongolian oak (Quercus mongolica) in 2004, the mortality continued to spread southwards in South Korea. Despite continued expansion of the disease and associated significant impacts on forest ecosystems, information is lacking about the origin and genetic diversity of R. quercus‐mongolicae. Restriction‐site‐associated DNA (RAD) sequencing was used to assess genetic diversity and population structure among five populations (provinces) of R. quercus‐mongolicae in South Korea. In total, 179 single nucleotide polymorphisms (SNPs) were identified among 2,639 RAD loci across the nuclear genome of the 54 R. quercus‐mongolicae isolates (0.0012 SNPs per bp), which displayed an overall low expected heterozygosity and no apparent population structure. The low genetic diversity and no apparent population structure among South Korean populations of this ambrosia beetle‐vectored fungus support the hypothesis that this fungus was introduced to South Korea.     

Bacterial shoot blight of sweet crab apple caused by Pseudomonas viridiflava

Sweet crab apple (Malus coronaria) is a popular ornamental tree planted in gardens and urban forests in South Korea. In 2018, severe symptoms were observed on street plantings of sweet crab apple in Jinju, South Korea including shoot blight: shoot tips, twigs and foliage of infected trees turned brown, and dried completely. The causal agent isolated from the disease lesions was identified as Pseudomonas viridiflava based on biochemical tests, pathogenicity, and 16S rRNA and rpoD gene sequencing. On artificial inoculation, this pathogen not only caused shoot blight on sweet crab apple, but also bulb rot and leaf blight on onion. Here, we report the occurrence of bacterial shoot blight caused by P. viridiflava in sweet crab apple for the first time in the world.     

Investigation of the mating‐type distribution of Raffaelea quercus‐mongolicae in South Korea

Raffaelea quercus‐mongolicae is a mycangial symbiont of a wood‐boring ambrosia beetle, Platypus koryoensis (Coleoptera: Curculionidae: Platypodidae), which is believed to be associated with oak mortality in South Korea. Since the first discovery of the disease in 2004, oak mortality has continued to spread across the country, and the pathogen has had a significant impact on forest ecosystems in the country; however, little is known regarding the biology of the fungus. The aim of this study was to develop markers to determine the mating types of individual isolates of R. quercus‐mongolicae collected across the country and then determine the mating‐type ratio in natural populations. To achieve this, partial sequences of MAT1‐1–3 and MAT1‐2–1 genes were amplified using degenerate primers and cloned. The new primer sets, which were specific to each mating‐type idiomorph, identified isolates as MAT1‐1 and MAT1‐2 mating types. The roughly equal frequencies of the two mating types suggest that sexual reproduction might have occurred in natural populations of R. quercus‐mongolicae in South Korea.     

Stem taper equation analysis for Larix kaempferi species in the Central Region of South Korea

Taper equation was developed to predict diameters at specific height for Larix kaempferi species in the Central Region of South Korea. The sampled trees that were collected through destructive sampling ranged from 0.60 to 47.90 cm DBH with total height ranging from 2.00 to 33.00 m. The dataset was randomly split into two: 80% for initial model fitting and 20% for model validation. The combined that means 100% dataset was used for final model fitting. Statistics of fit were used as criteria, including the coefficient of determination (R²), standard error of the estimate (SEE), bias (ē), the absolute mean difference (AMD), and the Akaike information criterion (AIC) values and weight (AICw), with a rank analysis being applied. Initial model fitting utilized a total of nine taper equations, with the three segmented taper equations and another three non-segmented determined for model validation and final model fitting. Kozak02 equation, which had not yet been evaluated for L. kaempferi species, indicated the best performance for the species in the Central Region of South Korea. Upon comparison, the ability of this study to predict diameters at specific height and stem volume was better than the existing taper equation for L. kaempferi in South Korea.     

First report of Rhytisma filamentosum causing tar‐spot disease on Salix koriyanagi

The occurrence of previously unknown tar‐spot disease on Salix koriyanagi was observed during surveys for forest disease outbreaks in Korea. The fungus associated with tar‐spot disease was identified as Rhytisma filamentosum based on morphological characteristics of the fungus and molecular sequencing of the ITS and 28S rDNA regions of two samples. To our knowledge, this is the first report of R. filamentosum on S. koriyanagi from Korea, following its first discovery on Salix integra in Japan.     

Morphology and molecular phylogeny of Erysiphe japonica var. japonica found on Quercus aliena in Korea

In October 2022, Erysiphe powdery mildew from the section Typhulochaeta was found on Quercus aliena for the first time in Korea. Based on morphological characteristics and molecular-phylogenetic analysis of the internal transcribed spacer region (ITS) and large subunit (LSU) gene sequences of the rDNA, the fungus was identified as Erysiphe japonica var. japonica. This is the first report of E. japonica var. japonica in Korea and the third report of this mildew on Q. aliena, with this current fungus-host association spreading to China and Japan. Based on Korean samples, this study provides detailed morphology and molecular phylogeny of E. japonica var. japonica.     

Notes on genus Eurydoxa Filipjev （Lepidoptera： Tortricidae） in China

Genus Eurydoxa Filipjev in China is reviewed and noted for the first time. Based on the present study, two species are recognized, including rhodopa Diakonoff and advena Filipjev. All available information for the species is reviewed and provided.     

Cymolomia hartigiana (Saxesen, 1840) (Lepidoptera: Tortricidae) attacking toAbies nephrolepis max. new to Daxing'anling, Heilongjiang, China

An Olethreutine speciesCymolomia hartigiana (Saxesen, 1840), attacking toAbies nephrolepis Max., is reported for the first time from Daxing'anling, Heilongjiang, China. The morphological characteristics are briefly re-described with illustrations. Also its damage and biology are noted. Foundation item: This study was carried out under the financial support by KOSEF (Korea Science & Engineering Foundation) with the program of “Korea and China Young Scientist Exchange Program” (2002–2003). Biography: *BYUN Bong-Kya (1963-), male, Ph.D., Researcher in Korea National Arboretum, Korea. Responsible editor: Chai Ruihai     

Indigenous parasitoids as effective natural enemies of <Emphasis Type="Italic">Phyllocnistis citrella</Emphasis> (Lepidoptera: Gracillariidae) in Korea

This study is aimed to investigate the occurrence of Phyllocnistis citrella Stainton (citrus leafminer; CLM), which has recently caused increasing damage to citrus farms in southern South Korea, and its natural enemies, which can act as biological control agents. In the present study, CLM monitoring using sex pheromone traps were conducted in the major citrus farms in the Jeju region in South Korea. Also a survey of parasites was carried out to detect the effective control agent for CLM. During the investigation from 2011 to 2015, a relatively large number of adult CLM (2,386,990) were observed in the sex pheromone traps. The mean annual occurrence of CLM was 477,398, which showed an increasing trend with the increase in temperature. A survey of parasites was conducted in November 2015. Six parasites were found, of which, Quadrastichus sp. and Sympiesis sp. showed the highest rates of parasitism. The mean rate of parasitism during the survey period was 3.97 %. We discovered four new species of parasites of CLM in South Korea.     

Testing of selected South African <Emphasis Type="Italic">Pinus</Emphasis> hybrids and families for tolerance to the pitch canker pathogen, <Emphasis Type="Italic">Fusarium circinatum</Emphasis>

Plantations of Pinus spp. constitute approximately 50% of the South African forestry industry. The first aim of this study was to develop a reliable inoculation technique to screen Pinus spp., for tolerance to infection by F. circinatum, which threatens pine forestry in South Africa. Inoculation of branches was compared with stem inoculations and we considered the number of branches or trees required to obtain statistically significant results. Furthermore, variation in the susceptibility of some Pinus families, clones and hybrids was considered. Results showed that branch inoculations were closely correlated with those from stem inoculations, and that it is important to consider branch and stem diameters when assessing susceptibility of trees. Subsequent trials using branch inoculations showed significant differences in F. circinatum tolerance amongst a range of pine species and hybrids of potential interest to forestry in South Africa. Significant differences in susceptibility were also found among clones of two P. radiata families. The most tolerant trees were P. elliottii × caribaea and P. patula × oocarpa hybrids, while the most susceptible species were P. patula, P. greggii and hybrids of these two. This is the first trial considering the susceptibility of Pinus hybrids, Pinus clones and some P. patula provenances, and the results indicate excellent potential for breeding for tolerance to pitch canker in South Africa. Application The accurate selection of disease tolerant planting stock for the South African forestry industry is crucially important for the continued sustainability of this important industry. The work described here provides valuable information on an artificial inoculation technique that will assist the industry in screening trees for tolerance to the pitch canker fungus, F. circinatum. It also provides some indication of the relative susceptibility of a number of Pinus spp., hybrids and families currently being evaluated in the country.     

The Eucalyptus stem canker pathogen Teratosphaeria gauchensis represents distinct genetic groups in Africa and South America

Teratosphaeria gauchensis (Capnodiales) causes a serious stem canker disease on commercially propagated Eucalyptus species in South America. Recently, this pathogen was detected for the first time in Africa. Very little is known regarding the biology or origin of T. gauchensis, but it has been suggested that it is native to South America. The aim of this study was to compare isolates from Africa and South America using microsatellite markers. Bayesian analysis conducted in STRUCTURE, principal coordinates analysis and a UPGMA dendrogram revealed two distinct genetic groups for these isolates. The South American isolates were more genetically diverse than those from Africa. Patterns of genetic diversity in Africa suggest that T. gauchensis could have been introduced into Zimbabwe before spreading north‐eastwards. The existence of the two genetic groups and high haplotype richness associated with the South American and Zimbabwean populations suggest that it will be more difficult to reduce the impact of disease caused by T. gauchensis in these regions than in those areas where there is limited genetic diversity.     

Genetic variation in natural populations of Abies nephrolepis Max. in South Korea

Abies nephrolepis Max. is a fir species occurring in Northeast China, the extreme southeast of Russia and Korea. In Korea, A. nephrolepis is one of only three native fir species growing in high, mountainous areas with a disjunct distribution. We investigated genetic variation in A. nephrolepis by examining 24 ISSR polymorphic loci in 248 individuals representing eight natural populations in Korea. The level of intra-population genetic diversity (H _e = 0.240) was similar to or slightly lower than that of plants with similar ecological traits and life history. Most of the genetic diversity was allocated among individuals within populations (G _ST = 0.082, Φ_ST = 0.041) and the number of migrants per generation (N _m ) was 5.56. Nei’s genetic distances were small (D = 0.027) and unrelated to geographic distances between populations. Implications for the conservation of genetic variation in A. nephrolepis in South Korea were discussed.     

Occurrence of leaf spot caused by Cristulariella depraedans on Acer ginnala

The occurrence of previously unknown leaf spots on Amur maples (Acer ginnala) has consistently been noticed during disease surveys in Korea since 2004. The symptoms included circular or irregular leaf spots that were greyish‐green to brownish‐grey in colour, which led to leaf senescence and premature defoliation. The morphological and cultural characteristics confirmed the identity of the causal agent as Cristulariella depraedans. This identification was supported by sequence comparisons based on ITS and LSU regions. The monospore isolate proved to be pathogenic when inoculated to the host plant under artificial conditions. This is the first report of C. depraedans infecting Amur maples in the world.     

First record of Quadrastichus mendeli,a parasitoid of Leptocybe invasa,in South Africa

Leptocybe invasa, the blue gum chalcid, is a well-known pest of Eucalyptus globally. Since it was first observed in the Mediterranean and Middle East in 2000, it has spread to other countries where Eucalyptus have been planted. Efforts to control it have included the release of a number of larval and pupal parasitoids. This report serves as the first record of the presence of Quadrastichus mendeli in South Africa, a parasitoid originally released as a biological control agent of L. invasa in Israel. The interactions and potential impacts on the other insects in the L. invasa galls will need to be investigated.     

Detection of individual trees and estimation of tree height using LiDAR data

For estimation of tree parameters at the single-tree level using light detection and ranging (LiDAR), detection and delineation of individual trees is an important starting point. This paper presents an approach for delineating individual trees and estimating tree heights using LiDAR in coniferous (Pinus koraiensis, Larix leptolepis) and deciduous (Quercus spp.) forests in South Korea. To detect tree tops, the extended maxima transformation of morphological image-analysis methods was applied to the digital canopy model (DCM). In order to monitor spurious local maxima in the DCM, which cause false tree tops, different h values in the extended maxima transformation were explored. For delineation of individual trees, watershed segmentation was applied to the distance-transformed image from the detected tree tops. The tree heights were extracted using the maximum value within the segmented crown boundary. Thereafter, individual tree data estimated by LiDAR were compared to the field measurement data under five categories (correct delineation, satisfied delineation, merged tree, split tree, and not found). In our study, P. koraiensis, L. leptolepis, and Quercus spp. had the best detection accuracies of 68.1% at h = 0.18, 86.7% at h = 0.12, and 67.4% at h = 0.02, respectively. The coefficients of determination for tree height estimation were 0.77, 0.80, and 0.74 for P. koraiensis, L. leptolepis, and Quercus spp., respectively.     

A preliminary report on decay and canker of Acacia richii caused by Inonotus rickii in China

An epidemic wood‐decaying fungus, Inonotus rickii, originating from South America, has spread to the Mediterranean area and southern China. We report the first observation of this fungus on Acacia richii in Panzhihua, southern China. It causes serious canker and decay on urban trees in the investigated area. In addition, phylogenetic analysis showed that the fungus from Panzhihua is closely related to isolates from Europe, South America, Mianyang and Hainan of China. Moreover, it was concluded that the isolates of the species previously reported from the USA do not belong to I. rickii.     

Die Verbreitung der Roßkastanien-Miniermotte Cameraria ohridella Desch. & Dimic (Lepid., Gracillariidae) in der Region Südtirol-Trentino

A survey on the present distribution of the horse chestnut leafmining moth, Cameraria ohridella Desch. & Dimic 1986, in Europe and in Italy is given: In Europe, within a period of 15 years, the leafminer – recently introduced into Central Europe – has settled in an area that spreads over 13 latitudinal and about 20 longitudinal degrees; in Northern Italy, an area of approximately 50,000 km² has been afflicted in the 5 years since the leafminer's introduction in South Tyrol and Julian Venetia in 1993.The development of the distribution in the region of South Tyrol and Trentino is shown: In the province of Bozen-South Tyrol, between 1995 and 1999 the moth has spread in all the three principal valleys (Eisacktal, Pustertal, Etschtal); in the Trentino province, first local attacks began only in 1998, near Trento and Riva, but spread over the entire Etschtal/Adige Valley in 1999. While in South Tyrol C. ohridella was introduced from the North (North Tyrol), the introduction into the Trentino occured from the South (Verona).At present the attacks in Trentino province are preponderantly low (resulting heavy only in the city of Trento and in Riva del Garda) and limited to altitudes ranging from 70 to 700 in. In South Tyrol, attacks are mainly heavy in altitudes ranging from 250 to 900/950 m, while they are low in the increasingly affected higher altitudes of 1,000 to 1,230 m. Numeric attack parameters are given to show attack intensities.The number of generations per year depends on the respective climatic conditions: in lower-altitudes, usually three generations develop in a year, but in higher altitudes (800 to 1,100 m) only two generations; in the climatically favoured area around the Lake Garda a (partial) fourth generation appears possible.The question of host plants (Aesculus sp., Acer sp.) and the larval parasitism of C. ohridella is discussed. The parasitism of the larvae, principally by Eulophidae (Hym., Chalcidoidea), was ascertained already in the first years of attack: In South Tyrol, 16 species of parasitoids appeared, and 8 in the Trentino province, but only two species were dominant: Minotetrastichus sp. and Pnigalio sp. The level of parasitism reached was low, comparable to other Central European countries.     

Ein neuer Obstschädling in Nordost-Iran

A new insect pest of fruit in the northeastern Iran Luperus kiesenwetteri Joannis was first found near Mashahd (northeast Iran) on May 14., 1975. It is the first record from Iran. The beetle was feeding on fruit trees such as pears, apple and cherry resulting in complete defoliation. Some specimens were found feeding on the alfalfa plants around the trees.L. kiesenwetteri is known from South Russia. Caucasus, Sarepta und Astrakhan. This is probably a new pest in Iran.